Oralytics

GoLang: Inserting records into Oracle Database using goracle

Posted on July 15, 2019 Updated on June 22, 2019

In this blog post I’ll give some examples of how to process data for inserting into a table in an Oracle Database. I’ve had some previous blog posts on how to setup and connecting to an Oracle Database, and another on retrieving data from an Oracle Database and the importance of setting the Array Fetch Size.

When manipulating data the statements can be grouped (generally) into creating new data and updating existing data.

When working with this kind of processing we need to avoid the creation of the statements as a concatenation of strings. This opens the possibility of SQL injection, plus we are not allowing the optimizer in the database to do it’s thing. Prepared statements allows for the reuse of execution plans and this in turn can speed up our data processing and applications.

In a previous blog post I gave a simple example of a prepared statement for querying data and then using it to pass in different values as a parameter to this statement.

dbQuery, err := db.Prepare("select cust_first_name, cust_last_name, cust_city from sh.customers where cust_gender = :1")  
if err != nil {
    fmt.Println(err) 
    return  
}  
defer dbQuery.Close() 

rows, err := dbQuery.Query('M')  
if err != nil { 
    fmt.Println(".....Error processing query") 
    fmt.Println(err) 
    return  
}  
defer rows.Close()  

var CustFname, CustSname,CustCity string 
for rows.Next() {  
    rows.Scan(&CustFname, &CustSname, &CustCity) 
    fmt.Println(CustFname, CustSname, CustCity)  
}

For prepared statements for inserting data we can follow a similar structure. In the following example a table call LAST_CONTACT is used. This table has columns:

• CUST_ID
• CON_METHOD
• CON_MESSAGE

_, err := db.Exec("insert into LAST_CONTACT(cust_id, con_method, con_message) VALUES(:1, :2, :3)", 1, "Phone", "First contact with customer")
if err != nil {
    fmt.Println(".....Error Inserting data") 
    fmt.Println(err) 
    return
}

an alternative is the following and allows us to get some additional information about what was done and the result from it. In this example we can get the number records processed.

stmt, err := db.Prepare("insert into LAST_CONTACT(cust_id, con_method, con_message) VALUES(:1, :2, :3)") 
if err != nil { 
    fmt.Println(err) 
    return 
}

res, err := dbQuery.Query(1, "Phone", "First contact with customer")  
if err != nil { 
    fmt.Println(".....Error Inserting data") 
    fmt.Println(err) 
    return  
} 

rowCnt := res.RowsAffected()
fmt.Println(rowCnt, " rows inserted.")

A similar approach can be taken for updating and deleting records

Managing Transactions

With transaction, a number of statements needs to be processed as a unit. For example, in double entry book keeping we have two inserts. One Credit insert and one debit insert. To do this we can define the start of a transaction using db.Begin() and the end of the transaction with a Commit(). Here is an example were we insert two contact details.

// start the transaction
transx, err := db.Begin()
if err != nil {
    fmt.Println(err) 
    return  
}

// Insert first record
_, err := db.Exec("insert into LAST_CONTACT(cust_id, con_method, con_message) VALUES(:1, :2, :3)", 1, "Email", "First Email with customer") 
if err != nil { 
    fmt.Println(".....Error Inserting data - first statement") 
    fmt.Println(err) 
    return 
}
// Insert second record
_, err := db.Exec("insert into LAST_CONTACT(cust_id, con_method, con_message) VALUES(:1, :2, :3)", 1, "In-Person", "First In-Person with customer") 
if err != nil { 
    fmt.Println(".....Error Inserting data - second statement") 
    fmt.Println(err) 
    return 
}

// complete the transaction
err = transx.Commit()
if err != nil {
    fmt.Println(".....Error Committing Transaction") 
    fmt.Println(err) 
    return 
}